Musnad Ahmad 1153:898

Bahz and ‘Affan narrated to us, they said: Hammad ibn Salamah narrated to us, he said: Qatadah and ‘Asim al-Ahwal narrated to us, from Mu‘adhah, from ‘Aishah, that she said: "I used to perform ghusl, I and the Messenger of Allah, may Allah bless him and grant him peace, from a single vessel, he would race me, and I would race him."